Modeling and Simulation of the Interference due to Digital Switching in Mixed-Signal ICs

The paper introduces a methodology for the evaluation of the interference noise, caused by digital switching activity, in sensitive circuits of a mixed-digital-analog chip. The digital switching activity is modeled stochastically as functions defined on Markov chains. The actual interference signal is obtained through the modulation of this discrete stochastic signal with real current injection patterns stored a priori in a pre-characterized library. The interference noise results from the propagations of these continuous stochastic signals through the linear network that models the chip posergrid, substrate and relevant package parasitics. The interference noise power spectral density is computed by linear frequency-domain analysis. The methodology is implemented using advanced numerical techniques capable of tacking very large problems.